Bursts of relativistic electrons from Jupiter observed in interplanetary space with the time variation of the planetary rotation period

Abstract

Bursts of Jovian electrons in the energy range 3-30 MeV have been detected to distances of the order of ! AU from the planet. The duration of each burst was about 2-3 days, and the maximum intensity increased with increasing distance from the sun. These events could not be correlated with known solar activity. The conclusion that these electrons originated at Jupiter and were accelerated within the Jovian magnetosphere is based on the following observations of three of these bursts. (1) The power spectrum of the temporal variations of the 6-to 30-MeV electron flux showed a persistent peak at Jupiter's rotation frequency, 2.8 X 10 -5 Hz (corresponding to the 10-hour rotation period) out to distances > l08 km from the planet; (2) the slope, or spectral. index, of the differential energy spectrum measured as a function of time displayed the 10-hour cyclic variation in the value of the index, which was earlier discovered by our group as being characteristic of the electrons within the Jovian magnetosphere; (3) the value of the spectral index was anticorrelated with the flux level of the 6-to 30-MeV electrons, an effect that was found inside the magnetosphere on the inbound pass; (4) the 10-hour variations of both the spectral index and the number density observed in the bursts analyzed so far are in phase with the corresponding variations inside the Jovian magnetosphere for R >• 50 Ra; and (5) overall, the bursts were anisotropic, their direction of propagation being toward the sun along the average interplanetary magnetic field. We also note that the particles in the bursts propagated across the average interplanetary magnetic field to reach Pioneer 10, and we discuss some of the implications. The analysis of these events provides a new tool for the study of the propagation of particles in the interplanetary medium. 157Pioneer II Launch, Do• 96

Jupiter's radiation belts

“…This latter mechanism , i. e. , the beam-cyclotron irstability, is Following the observations by Chenette et al ( 1974Chenette et al ( , 1975 high-order magnetic multipol-es in Jupiter' s main field (Dessler and Hill , 1975). This view is somewh at difficult ot reconcile with the rnagnetometer observations (e.g.…”

“…1974) . M o r e o v e r , when the s p a c e c r a f t was within -~ 1 AU of Jup iter , such enhancements we re found to be modulated at Jup iter ' s rotation pe riod (Chenette et al , 1974; . The sam e patte rn held for Pioneer 11.…”

The effect of adiabatic focusing upon charged-particle propagation in random magnetic fields

“…The Jovian electron bursts recorded on Pioneer 10 result from the inward propagation of low ~igidity particles along interplanetary fields (Chenette, et al 1974, Teegarden, et al 1974, Smith, et al 1975. The supercoherent mode does not apply here, but quasi-coherent propagation into converging fields is predicted by equation (57), for relatively weak focusing, and by the pseudodiffusive idealization, for strong focusing.…”

3–20 MeV Electrons in the Inner Three‐dimensional Heliosphere at Solar Maximum:UlyssesCOSPIN/KET Observations

“…This makes Jovian electrons very interesting and nonredundant with solar flare electrons for the modeling of interplanetary propagation. Jovian electron studies resulted in the first strong observational evidence for a diffusive transport of electrons perpendicular to the mean heliospheric magnetic field (Chenette, Conlon, & Simpson 1974;Hamilton & Simpson 1979).Galactic cosmic ray electrons.-At distances beyond 10 AU in the ecliptic, Galactic cosmic ray (GCR) electrons are the dominant population . …”